hermes

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Overview

hermes is an Android dynamic method hooking playground project.
It combines Kotlin/Java APIs with a Rust native core to test ART method interception and replacement. It supports Android 8.0+ and the following ABIs: armeabi-v7a, arm64-v8a, x86, x86_64.

Repository layout:

• hermes/: core library (Kotlin + Rust)
• app/: sample app (Jetpack Compose UI for visual hook testing)

Installation

Hermes is published on Maven Central:

Add dependency in your app/library module:

dependencies {
    implementation("io.github.enuwbt:hermes:0.1.1")
    implementation(kotlin("reflect")) // required for KFunction-based APIs
}

If needed, ensure repositories include Maven Central:

dependencyResolutionManagement {
    repositories {
        google()
        mavenCentral()
    }
}

Usage

1. Define hooks with DSL

import io.github.enuwbt.hermes.defineInterceptsOf

MyClass::class.defineInterceptsOf {
    method("sum", Int::class, Int::class) {
        implementation = { a: Int, b: Int ->
            self.memberFunction()
            val originalValue = original(a, b) as Int
            originalValue + 1
        }
    }
}

2. Hook a reflected method directly

import io.github.enuwbt.hermes.Hermes
import io.github.enuwbt.hermes.InterceptCallback

val method = MyClass::class.java.getDeclaredMethod("sum", Int::class.javaPrimitiveType, Int::class.javaPrimitiveType)
Hermes.intercept(method, object : InterceptCallback() {
    override fun onInvoke(receiver: Any?, args: Array<out Any?>): Any? {
        val originalValue = original(receiver, args) as Int
        return originalValue + 10
    }
})

3. Hook by function reference (Class::method.intercept)

import io.github.enuwbt.hermes.intercept
import io.github.enuwbt.hermes.InterceptCallback

MyClass::sum.intercept(object : InterceptCallback() {
    override fun onInvoke(receiver: Any?, args: Array<out Any?>): Any? {
        val originalValue = original(receiver, args) as Int
        return originalValue + 100
    }
})

Requirements

• Android Studio (latest stable recommended)
• JDK 11
• Android SDK / NDK (as required by Gradle config)
• Rust toolchain (cargo)
• Rust Android targets (e.g. armv7-linux-androideabi, i686-linux-android, x86_64-linux-android, aarch64-linux-android)

Build

./gradlew cargoNdkBuild
./gradlew assembleDebug

Run the Sample

1. Install the app module on a device/emulator
2. Open the app and use each test item:
   • Call: run current implementation
   • Hook: install interception for that method
   • Result: show execution result

Notes

• This project is intended for research/testing purposes.
• Behavior may vary depending on Android version and CPU architecture.
• Do not commit local.properties (environment-specific).

Credit

• LSPlant (https://github.com/LSPosed/LSPlant)
• pine (https://github.com/canyie/pine)

Third-Party Licenses

• xz-embedded: 0BSD (hermes/src/main/rust/third_party/xz-embedded)

License

This project is licensed under the MIT License.
See LICENSE for details.